Image analysis – Image compression or coding – Adaptive coding
Reexamination Certificate
2000-05-18
2001-09-18
Chen, Wenpeng (Department: 2624)
Image analysis
Image compression or coding
Adaptive coding
C382S251000, C375S240020, C375S240030
Reexamination Certificate
active
06292590
ABSTRACT:
TECHNICAL FIELD
This invention relates to a coding device and a coding method for encoding an image on the basis of unit blocks and also to a decoding device and a decoding method for decoding image data encoded also on the basis of unit blocks. The present invention also relates to a recording medium carrying programs that are recorded thereon so as to be executed by an information processing apparatus for such encoding and decoding operations.
BACKGROUND ART
With conventional coding techniques using blocks, a neighbouring block is defined on the basis of self correlation of an image and the encoding operation is conducted on a policy of eliminating redundancy within the block. Various shapes are found when evaluating an image by means of neighbouring blocks, including those for plane areas and those for edges.
In ordinary encoding operations, while redundancy may be eliminated with ease from plane areas in order to compress the data to a large extent, edges are disadvantageous in terms of compression because of the large amount of information involved there so that distorted and unbalanced quantization can occur as a result of encoding. While the resultant degradation of the image quality may be unrecognizable in certain occasions due to the masking effect of the sight, an increased amount of information has to be used to alleviate the degree of visual degradation.
DISCLOSURE OF THE INVENTION
In view of the above identified circumstances, it is therefore an object of the present invention to provide a coding apparatus and a coding method that can raise the level of correlation in a block to reduced the amount of information necessary for coding.
Another object of the invention is to provide a decoding apparatus and a decoding method that can decode image data encoded on the basis of unit blocks in a simple fashion.
According to the invention, there is provided a coding apparatus for encoding an image signal on the basis of unit blocks containing a plurality of pixel data, said apparatus comprising a coding section for encoding a plurality of pixel data contained in a block and outputting coded data, a pixel exchange section for causing said plurality of blocks to exchange at least a pixel data therebetween and a detecting section for detecting the amount of information produced by said coding section at the time of encoding said plurality of pixel data for the case of existence of exchange of pixel data or the case of non-existence of exchange of pixel data, said coding section being adapted to output the encoded pixel data of said block for the case of existence of exchange of pixel data or the case of non-existence of exchange of pixel data, whichever involving the smaller quantity of information as detected by said detecting section.
According to the invention, there is provided a decoding apparatus for decoding encoded data obtained by dividing an image signal into a plurality of blocks, each containing pixel data, and causing the blocks to exchange at least a pixel data therebetween so as to reduce the amount of encoded information, said apparatus comprising a decoding section for decoding a plurality of pixel data out of the encoded data for each block and a pixel reverse-exchange section for carrying out a reverse-exchange operation of recovering the pixel data exchanged between the blocks for the plurality of pixel data decoded by said decoding section for each block.
According to the invention, there is also provided a coding method for encoding an image signal on the basis of unit blocks containing a plurality of pixel data, said method comprising steps of detecting the amount of information produced at the time of encoding said plurality of pixel data for either the case of existence of exchange of pixel data and the case of non-existence of exchange of pixel data and outputting the encoded pixel data of said block for the case of existence of exchange of pixel data or the case of non-existence of exchange of pixel data, whichever involving the smaller quantity of information.
According to the invention, there is provided a decoding method for decoding encoded data obtained by dividing an image signal into a plurality of blocks, each containing pixel data, and causing the blocks to exchange at least a pixel data therebetween so as to reduce the amount of encoded information, said method comprising steps of decoding a plurality of pixel data out of the encoded data for each block and carrying out a reverse-exchange operation of recovering the pixel data exchanged between the blocks for the plurality of pixel data decoded by said decoding section for each block.
According to the invention, there is provided a recording medium storing a computer-controllable program recorded in it for encoding an image signal on the basis of unit blocks containing a plurality of pixel data, said program comprising steps of detecting the amount of information produced at the time of encoding said plurality of pixel data for either the case of existence of exchange of pixel data and the case of non-existence of exchange of pixel data and outputting the encoded pixel data of said block for the case of existence of exchange of pixel data or the case of non-existence of exchange of pixel data, whichever involving the smaller quantity of information.
According to the invention, there is also provided a recording medium storing a computer-controllable program recorded in it for decoding encoded data obtained by dividing an image signal into a plurality of blocks, each containing pixel data, and causing the blocks to exchange at least a pixel data therebetween so as to reduce the amount of encoded information, said program comprising steps of decoding a plurality of pixel data out of the encoded data for each block and carrying out a reverse-exchange operation of recovering the pixel data exchanged between the blocks for the plurality of pixel data decoded by said decoding section for each block.
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“New ADRC for consumer digital VCR,” T. Kondo et al., 8th International Conference on Video, Audio and Data Recording, 1990, pp. 144-150.*
“Block adaptive quantization of images,” P. Monet et al., IEEE Transactions on Communications, vol. 41, No. 2, Feb. 1993, pp. 303-306.
Horishi Takashi
Kondo Tetsujiro
Chen Wenpeng
Frommer William S.
Frommer & Lawrence & Haug LLP
Sony Corporation
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